Adler Barbour Cold Machine Cold Plate Temperature

[UncleRico]

I'm trying to determine whether my Cold Machine (installed 1999) is malfunctioning. My fridge runs nearly constantly, and my cold plate only gets down to about 15 F on my IR thermometer. I'm currently waiting on an adapter so I can connect the compressor low side to my R134a quick-connect gauges, but I'm wondering how cold the cold plate should get. For those with similar systems, how cold does your cold plate get?

[Bellinghamster]

Before you futz with the refrigerant, do you have a way to accurately measure the current of the compressor? Current is a pretty good indicator of level of charge. Typically 4.5-5A (at 12.5VDC) when the cold plate is cold, lower if undercharged, higher if overcharged, however it is influenced by compressor speed, so best to check the current rating on the nameplate or manual for your system.
Connecting gauges can introduce new problems - if the system is under vacuum when you connect you can suck in air. If you don't have your gauge hoses purged properly you will suck in air. When you disconnect your gauge you will lose some refrigerant (both from the fitting and whatever is in your hose).
Do you have a eutectic holding plate? If so, what model?

[UncleRico]

The evaporator itself just has an A/B product sticker: model no. 3311. (I wrote "cold plate" in my original post, but it's obviously an evaporator system.) It's drawing more like 7 amps, so maybe overcharged, but my real question is: What evaporator temperature should my system be producing? I think that I really care about is the evaporator temperature, and everything else (draw, refrigerant charge) only matters to produce that. I'd like to know when I should be satisfied that the system is operating properly.

[Bowdrie]

Trying to figure out "absolutes" as regards to evaporator temp is chasing your tail.
First find out why your compressor is drawing close to double what it should.
1, Overcharged?
2, Bad fan/air flow/ventilation?
3, Air in system?
4, Ambient air temps too high?
5, Clogged/partially clogged filter or cap tube?
All refrigeration works on the principle of allowing a refrigerant to "boil off", as it changes from a high-pressure liquid at the inlet of the evaporator to an ever decreasing in pressure gas as it travels the length of the evaporator coils.
As the refrigerant gas expands its ability to continue to absorb heat reduces, its expansion ratio starts decreasing.
Power to do work, (remove BTUs,) is a curve, there's a "fat" part of the curve where efficiency is high, (watts in for BTUs removed,) and lean parts, (watts in for less BTUs removed).
It's all inter-related with compressor capacity, (how much weight of refrigerant can it move per unit time and at what pressure can it develop without exceeding its electrical parameters,) now we'll add condenser capacity/condensing temperature/evaporator capacity and the specifics of the refrigerant.
If you're looking for an "absolute" you're chasing a moving target.

[Bellinghamster]

For some comparison datapoints - I have a Dometic small evaporator box system with a BD35 compressor (currently for sale!) that draws about 5 amps at 12.5VDC (including condenser fan), refrigerant temp at the exit of the cap tube on top of the evaporator box is about -5F when the system is running in free/open air (not installed in an icebox) Ambient temperature 60-65F). The bottom of the evaporator box is around 10F. The large evaporator box system with a BD50 compressor that I have installed in my boat has similar current and temperatures. Current decreases a bit when the fridge/freezer is cold. I have very good airflow through the condenser and it's ducted out of the cabinet it's installed in to keep the condensing temp as low as practical.

[GordMay]

FWIW: Richard Kollmann “... would again test the system with thermostat disconnected from control module and jumper on module thermostat terminals. Now if you let it run without it stopping evaporator temp will drop to minus 16 degrees below zero as long as there is no air movement in side box, an compressor never sysles cycles off...”
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